Our site is implemented using SXA. Currently,caching is set on CloudFlare for our site.  Due to this caching, any media file(eg: pdf, excel) we update in sitecore does not reflect on the site. I can download updated media item by appending some query string to the media url but not using the original URL. 

Is there an ideal solution for this issue? 

I can think of adding a query string params based on the media modified date? is this a right approach?

any advice and suggestions on this will be greatly appreciated.